Stretching machine



Sept. 29, 1964 E. KAMPF sTRETcHING MACHINE Filed July l, 1963 5 Sheets-Sheet 1 E. KAMPF STRETCHING MACHINE Sept. 29, 1964 3 Sheets-Sheet 2 Filed July 1, 1963 Eb BY HTTOHNEYS Sept. 29, 1964 E. KAMPF STRETCHING MACHINE 3 Sheets-Sheet 5 Filed July 1, 1965 IN VEN TOR. Eberhard fa/@f )5w/wf L/wu/ H T TUR/VE V5 United States Patent C) e claims. (ci. 26-57) The present invention relates to a stretching machine for stretching webs, foils or the like, for instance of paper, textile, plastic material, synthetic materials and the like.

This application is a continuation-impart of my copending application Serial No. 44,781, filed July 22, 1960, for an invention entitled Stretching Machine, now abandoned.

It is an object of the present invention to provide an improved stretching machine of the above-mentioned general type.

It is another object of 4the present invention to provide a stretching machine for stretching webs in width and/ or length to a variable degree.

It is a still further object of this invention to provide a stretching machine of the above-mentioned type which is relatively simple in construction and operation yet efficient and reliable in operation.

It is a specific object of the invention to provide a stretching machine for web material in which gripping means engage the edges of the web and are thereupon moved along divergent paths by a screw conveyor type of driving means.

These and other objects and advantages of the invention will appear to those skilled in the art as the description proceeds with reference to the accompanying drawings wherein:

FIG. 1 is a somewhat schematic plan view of a machine embodying the present invention, certain parts being omitted for clarity of illustration and other parts being partially broken away;

FIG. 2 is an enlarged fragmentary sectional view taken along the line 2 2 of FIG. 1;

FIG. 3 is a fragmentary perspective view of a portion of the apparatus; and

FIG. 4 is an enlarged fragmentary sectional view taken substantially along the line 4 4 of FIG. l.

The machine shown in FIG. l comprises a main frame structure designated generally at 2. The frame 2 supports infeed guide rolls 4 and a discharge conveyor roll system 5 for respectively receiving and guiding a web to be stretched into and from the machine. The roll system 5 may include edge trimming or other cutters if desired. The frame 2 supports two pairs of parallel, closed loop guide tracks 6 and 8. Both pairs of tracks are identical except that one is a mirror image of the other, as will be obvious to those skilled in the art. The outer track 6 and inner track S are shown in greater detail in FIGS. 2 through 4, which will be referred to in greater detail hereafter. However, the tracks 6 and 8 are parallel to each other but spaced apart to define a guideway 1l) therebetween. The tracks 6 and 8 are supported on any suitable support structure, such for example, as the posts 12 indicated in FIGS. 2 and 4. Similar posts (not shown) are provided for the inner track 8.

The posts 12 which support the tracks 6 and 3 are carried by movable base members (not shown), respectively mounted lon transverse slides 14 and 17. The slides 14, of which there are two, are respectively mounted adjacent' opposite ends of a transverse screw shaft 16 journalled on the frame 2. A, The respective end portions of the shaft I6 are provided with threads 18 and Ztl of opposite hand so that rotation of the shaft by means of hand wheel 22 will effect lateraladjustment of 3,l5,433 Patented' Sept. 29, 1 964 ice the slides 14 towards or from each other, depending upon the direction of rotation of the shaft. In like manner, the slides 17 are mounted on end portions of a transverse shaft 24 journalled in frame 2 and which end portions are provided with threads 26 and 28 of opposite hand. Rotation of shaft 24 by means of hand wheel 30 will obviously effect lateral adjustment of the slides 17. Thus, adjustment of the two shafts 16 and 24 may be accomplished as desired to regulate or adjust the degree of separation of the pairs of tracks 6 and 8. The portion of the tracks 6 and S adjacent the slides 14 define the entrance portion of the machine whereas those portions adjacent the shaft 24 define the discharge end of the machine, as will be described. As shown, the tracks 6 and 8 and the space 10 therebetween define a pair of closed or loop guides having initial or entrance portions 32 substantially straight and parallel to each other, diverging portions 34, diverging outwardly from each other in the direction toward the discharge end of the machine and defining therebetween a stretching zone and straight parallel portions 36 defining the discharge ends of the guide means. A multiplicity of gripper carriages 38 are individually and separably movable along the tracks 6 and 8. FIG. 3 more clearly shows the structure and arrangement of the gripper carriages 3S, as do FIGS. 2 and 4. Referring to FIG. 3, however, each gripper carriage 38 comprises a body portion having a leg or web 39 extending downwardly in the space 10 between the tracks 6 and 8. The leg 39 lits fairly snugly but is easily slidable in the space 10. At its lower end each carriage 3S is provided with a downwardly projecting stud or pin 40. As viewed in FIG. 3, the near side of each carriage 3S is provided with two vertically spaced rollers 42, one engaging the upper surface of track 8 and the other engaging the under surface thereof. In addition, the rollers 42 are laterally offset so that the upper one is at the right hand side of its carriage and the lower one is at its left hand side thereof. On the opposite or far face of each leg 39 is another pair of rollers 44 (only one of each visible in FIG. 3) which are spaced and staggered similar to the rollers 42 but wherein the upper roller is at the left side of the carriage whereas the lower roller is at the right hand side. Thus, the four rollers 42 and 44 on each carriage not only support the same on the tracks 6 and 8 but also prevent cooking orl tilting movement of the carriages in a plane parallel to the direction of movement along tracks 6 and 8.

At a level above the tracks 6 and S each carriage 38 is provided with an inwardly extending ange member 46 spaced downwardly from an upper liange 48. The upper flange 48 is bifurcated and pivotally supports a gripping element 5t? pivoted thereon by pin 52.

Referring next to FIG. 2, it will be seen that the pivoted gripping elements 5G are swingable between the full and dotted line positions shown at the left of FIG. 2. A tension spring 54 has one end secured to anv upwardly projecting portion 51 of gripping element 50 and its other end secured to a bracket 56 formed on the carriage 38. With the gripping element Si) in the full line position of FIG. 2, it is ineffective to clamp the edge of a web whereas in its dotted line position the lower end 57 of the element Sli tends to wedge against the upper surface of flange 46, under the influence of spring 54, and thus is eective to grip and clamp an edge portion of a web 6h to the carriage 38.

The frame 2 of FIG. 1 pivotally supports a pair of adjustable plates 62, each preferably pivotally mounted to the frame 2 on a Vertical axis 64 for lateral swinging movement. The other ends of the plates 62 are suitably connectedto transverse slides 66 mounted on the end portionsof a further transverse shaft 63 having opposite end portions provided with threads 7) and 71 of opposite hand. When the shaft 68 is rotated by hand wheel 72, the divergence of the plates 62 may be regulated, depending upon the direction of rotation of the shaft 68. The transverse adjustment accomplished by the shafts 16, 2 and 68 are known in general principle to the prior art and need not be further described herein. lt is further to be noted that, if desired, the means defining the axes 64 may be made laterally adjustable to vary the spacing between those axes.

Each plate 62 has journalled thereon a horizontal screw conveyor member '74 so arranged that it may be adjusted to exact parallelism with the portions 34 of the guide means defined by tracks 6 and S and to underlie and extend below the spaces it? between the tracks 6 and S. As seen in FG. 3, the downward projecting stud or pins il on each of the carriages 38 is of such length as to extend into the helical groove '76 of its associated screw 74. A suitable motor 7S is mounted on each plate 62 and arranged to drive its associated screw 74 in rotation through gearing 80 or the like. It is contemplated that the motors 73 be so constructed and arranged that they rotate at the same speed and are synchronized with other drive means to be mentioned later. Obviously, however, the screws 74 may be driven through suitable transmission means from a common power source for the entire machine.

FlG. 4 illustrates, schematically, one end portion of one of the closed trackways and wherein a vertical shaft 32 is journalled in a suitable manner on its associated slide i4 (not shown in FIG. 4) and is connected to a main drive of the machine (also not shown). lt will be obvious to those skilled in the art how any suitable driving motor may be flexibly connected to the shaft 32 to effect rotation thereof while still permitting lateral adjustment along with slide M. Keyed to but slidable on the shaft 82 is a clutch plate til-i and a back-up plate is also mounted on the shaft 8?; in abutment with shoul* der 83. The clutch plates 84- and S6 are spaced apart and provided with friction driving faces SS engageable with opposed faces of a sprocket or transfer wheel 9@ journalled on the shaft S2 as by means of sleeve bearing 92. The transfer wheel 90 is provided with outer projecting fingers 93 at its peripheral edge so spaced that the spaces therebetween receive the downwardly projecting pins or studs itl on the carriages 33. The tracks o and S adjacent the wheel 9G are of arcuate shape and extend con centrically about the shaft SZ. Thus, it will be seen that the transfer wheel 9d is effective to engage and move carriages 3S from the outer run of the tracks o and S to the entry end of the straight portions 32 thereof. Suitably supported on the slides lili are cam plates 94. The cam plates 9d, may, if desired, extend substantially the length of the machine to overlie the space between the inner and outer runs of each pair of tracks 6 and 8 and terminate in cam portions at the other end of the machi e, as will be further descibed later. cam plates @Il are arranged so that the portions of their peripheries or outer edges are in position to engage the upward' The ty projecting portions l of "ripping elements 5? to cam same outwardly to the full line positions shown in 4. Thus, the grippers are open as the carriages approach the straight portions SZ of the trackways.

The rollers 4 guide a web d@ of stretchable material into the machine between the straight portions 32 of the trackwar's with the edges of the web in position to be en* gaged by the gripper elements 5?. As shown in "11. 1, the cam plates 94 are so shaped that the portions Eil of the grippers pass over a fall ast/ay portieri tll after each carriage has entered the straight portion 32 of the guide means. This releases the gripper elements Sti to their respective springs 54 to clamp the edge of the web titl to the upper surface of that particular earring-eV it is to be understood that the gripper carriages Sti are provided in sufiicient numbers so that there isa continuous supply thereof `approaching the transfer wheel 9i? and a continuous row thereof extending alon g the working run of the guide means, that is the portions 32, 34 and 36, and preferably a suiiicient number to extend in somewhat spaced relation for the full length of the outer runs of the trackways.

As shown, the screws '74 are provided with the helical grooves 76 which are of changing pitch along the length of the screws. In other words, the axial space between successive convolutions of the groove 76 at the left hand end as seen in FIG. 1 is less than the spacing between those convolutions at the right hand end of each screw.

As will be obvious, operation of the machine effects clamping of successive portions of the web 69 by successive grippers on carriages 33, which are in abutment with each other, at the entry of the straight portions 32 f the trackways and those carriages are then carried along by the moving web 6@ and the thrust from transfer wheel until their depending studs or pins 4t) enter the helical groove 75 of the associated screw 74. The pitch of the groove 76 at the entry end of its screw and the speed of rotation of each screw is such that the entry end of the groove 76 arrives in time to engage the pin 40 of the next succeeding carriage 38. Preferably, a short length of each screw '74 adjacent each end thereof is so formed that the helical groove 76 is of uniform pitch for one turn or more. Thus, as the screws are driven in rotation, they enforce movement of the carriages 353 along the diverging portions 34 of the trackways, through the stretcl ing Zone, and effect lateral stretching of the web since the edges thereof are clamped to their respective carriages. Due to the increasing pitch of the screws 74, the carriages 33 are spread apart in a longitudinal direction as they progress along the divergent portions 34 of the trackway and thus also effect longitudinal stretching of the web 66. Where the web 6) is a thermoplastic material, it is desirable to provide heating means generally indicated at itil? to keep tue temperature of the web sufficiently ele- Vated so as to facilitate permanent stretching thereof. Also, if necessary or desirable, heating means may be provided to preheat web 6l) before it enters the stretching zone.

After each of the carriages 38 has left the discharge end of its associated screw 74, it is carried along the straight portions 35 of the trackway by movement of the stretched web and by a further conveyor, which will be described. it is to be pointed out that reeling means are preferably provided to withdraw the stretched web from the machine and thereby assist in causing movement of the stretched web to the right adjacent the discharge end of the machine shown in FG. 1, although such means are not essential.

As previously stated, the cam plates 9dpreferably extend to the discharge end of the machine and the inner edges thereof are provided with riser portions 104 ar ranged to engage the upper ends Si of gripper elements Sti (see FIG. 2) to swing the upper ends thereof outwardly and thus release the edges of the stretched web 60 and release the carriages from the web for return along the outer rims of the trackways back to the transfer wheel 9u. Preferably the cams 9d are so configured that the grippers are permitted to close again shortly after leaving the stretched web 60 and are not opened again until just before they embrace the web 60 at the entrance end of the machine. In this way friction between grippers 5t) and plate 94 is eliminated during return movement of the carriages.

At the discharge end of the machine vertical shafts lil are journalled in slides i7, in the manner described with reference to vertical shafts 82. The shafts 106 are likewise provided with slidably keyed friction plates 103 and backup plates Htl, similar to the plates d4 and 85 of FIG. 4. A sprocket wheel lf2 is journalled on shaft Miti between the plates 168 and litt) and is frictionally driven thereby. The sprocket wheels 112 are provided with sprocket teeth 114- arranged at a level above the screws 74.

A conveyor chain 115 is trained about the sprocket wheel M2 and about an idler sprocket 115, shown in FIG.

1. The idler sprocket is journalled on the same support means (not shown) that supports the tracks 6 and 8 so that it will always be in the same position relative to the tracks. The inner track 8 of each pair of tracks is preferably provided with a guide channel 118 secured to its under surface and in which a portion of the conveyor chain 116 slides. The conveyor chain 116 is provided further with a multiplicity of outwardly extending fingers 120 extending laterally outwardly from the sprocket wheel 112 at a level above the upper surface of screws 74 and in position to engage the upper portions of the pins or studs 40 depending from carriages 38 while they are still in engagement with the screws 74. The sprocket wheels 112 are driven in timed relation to the transfer wheel 90 and screws 74 so that the fingers 120 of the chain 116 engage the trailing edge of successive pins 40 slightly before those pins leave the grooves 76 of the conveyor screws 74. Thus, after each carriage has left the discharge end of its associated screw 74, it is carried along by a finger 120 on chain 116 to and past the riser portion 104 of cam plate 94, around the arcuate trackway defined by tracks 6 and 8 and back along the outer run of the trackway toward transfer wheel 90. As shown in FIG. l, the carriages 38 are carried by the fingers 120 back to a position short of the transfer wheel 90. As the chain 116 and its fingers 120 pass around idler sprocket 115, the carriage 38 just released thereby joins the abutting supply of carriages awaiting engagement with the transfer Wheel. Each successive carriage 38 released by the chain 116 serves to advance the group of carriages between that point of release and the transfer wheel 99.

Thus, means are provided for continuously feeding gripper carriages to the edge of a Web to be stretched, clamping those edges to the carriages, advancing the carriages in a manner to stretch the web both laterally and longitudinally, to release the carriages from the web, and then transfer successive individual carriages back to the starting point of the machine. i

Obviously, the groove 76 of screws 74 could be of uniform pitch throughout the length of the screw if it were desired to merely effect lateral stretching of the web 60 without any longitudinal stretching thereof. Furthermore, the invention contemplates the use of screws of variable pitch to effect only longitudinal stretching of a web, as will be obvious to those skilled in the art.

Referring again to FIGS. 2 and 4, the upper friction plate 84 of FIG. 4 and the upper friction plate 108 of FIG. 2 are keyed to their respective shafts for vertical sliding movement thereon but for enforced rotation therewith. Numerals 130 indicate keys by which this may be accomplished. Compression springs 132 (FIG. 2) and 134 (FIG. 4) bear against the upper friction plates and react against adjustable hand wheels 136 threaded to the upper ends of their respective shafts. By this construction, the hand wheels 136 may be adjusted to vary the pressure exerted by springs 132 or 134 on their respective pressure plates to thus regulate the maximum torque transmitted. It is preferable that such friction drives be provided in the event that one or more of the carriages may jam or lock on the trackways.

When heated thermoplastic materials are being stretched, it is inevitable that the grippers will also absorb heat and possibly to an undesirable degree. In such cases, suitable cooling means (not shown) may be provided for cooling the carriages during their return travel from the discharge end toward the entrance end of the machine.

It is to be pointed out that the stationary cam plates 94 could be replaced by circular plates mounted on the upper ends of shafts 82 and 106 for rotation therewith.

While a single specific embodiment of the invention has been shown and described herein, it is to be understood that the same is merely illustrative of the principles involved and that other modifications may be resorted to within the scope of the appended claims.

I claim:

1. In a web stretching machine: means for guiding a web of material to and through a stretching zone; said stretching zone being defined by guide means having rectilinear portions arranged in diverging relationship adjacent the opposed side edges of said web; a plurality of separate and independently movable grippers movable along each of said guide means and each having means thereon for securely gripping the edge of said web; a screw rotatably mounted on said machine adjacent and parallel to each of said guide means; means on each of said grippers removably engaging a thread of its associated screw; and means for rotating said screws to transport all said grippers along their respective guide means in the direction of their divergence whereby to stretch said web in a transverse direction as it progresses through said zone.

2. A machine as defined in claim 1 wherein the pitch rof each of said screws increases in the direction of divergence of said guide means whereby the web gripped by said grippers is stretched in both its transverse and 1ongitudinal directions as it progresses through said zone.

3. A machine as defined in claim 1 wherein each gripper is provided with rollers engaging said guide means whereby each is supported thereon for independent movement therealong; each of said screws being arranged below its associated guide means; said thread engaging means comprising a depending projection on each gripper, extending downwardly therefrom into engagement with its associated screw.

4. A machine a defined in claim 1 wherein each of said guide means extends beyond each end of its associated screw whereby each gripper may be guided by its guide means into engagement with one end of its screw at the entrance to said zone and may continue along its guide means after leaving the other end of its screw.

5. A machine as defined in claim 4 wherein each of said guide means defines a closed loop whereby each gripper leaving said other end of its screw may be guided backto said one end thereof.

6. A machine as defined in claim 4 including feeder means adjacent said one end of each of said screws for advancing individual grippers along said guide means to said one end of said screws in timed relation to rotation of said screws.

References Cited in the file of this patent UNITED STATES PATENTS 2,473,404 Young June 14, 1949 2,755,533 Miller July 24, 1956 2,923,966 Tooke et al. Feb. 9, 1960 FOREIGN PATENTS 112,553 Great Britain Jan. 17, 1918 14,792 Great Britain of 1905 

1. IN A WEB STRETCHING MACHINE: MEANS FOR GUIDING A WEB OF MATERIAL TO AND THROUGH A STRETCHING ZONE; SAID STRETCHING ZONE BEING DEFINED BY GUIDE MEANS HAVING RECTILINEAR PORTIONS ARRANGED IN DIVERGING RELATIONSHIP ADJACENT THE OPPOSED SIDE EDGES OF SAID WEB; A PLURALITY OF SEPARATE AND INDEPENDENTLY MOVABLE GRIPPERS MOVABLE ALONG EACH OF SAID GUIDE MEANS AND EACH HAVING MEANS THEREON FOR SECURELY GRIPPING THE EDGE OF SAID WEB; A SCREW ROTATABLY MOUNTED ON SAID MACHINE ADJACENT AND PARALLEL TO EACH OF SAID GUIDE MEANS; MEANS ON EACH OF SAID GRIPPERS REMOVABLY ENGAGING A THREAD OF ITS ASSOCIATED SCREW; AND MEANS FOR ROTATING SAID SCREWS TO TRANSPORT ALL SAID GRIPPERS ALONG THEIR RESPECTIVE GUIDE MEANS IN THE DIRECTION OF THEIR DIVERGENCE WHEREBY TO STRETCH SAID WEB IN A TRANSVERSE DIRECTION AS IT PROGRESSES THROUGH SAID ZONE. 